RELATION TO OTHER APPLICATIONS
This application is related to my co-pending U.S. patent application Ser. No. 07/387,520.
1. Field of the Invention
This invention is concerned with the containment and removal of marine pollution, preferably at or near its immediate source, to prevent further dispersal of the pollution into the environment. The invention has particular application to containment and recover of good clean oil in the open sea, in rough water under adverse weather conditions.
2. Discussion of the Prior Art
Major spills of pollution material such as crude oil occur infrequently in the marine environment but when they do happen, the results can be catastrophic. The disastrous effects stem not so much from the actual localized flow of the pollution from a point source, but from the uncontrolled widespread dispersal of the material over the water surface due to wave, wind and current action. If the flow of pollution can be substantially contained at or near the source, the environmental impact of the spill is minimal.
Although the environmental effects of a crude-oil spill are of concern, the economic loss of that natural resource is also of importance. Once the spill has spread over a large area, even if the thin layer of scum can be recovered, it becomes so badly emulsified by the water that the scum cannot be economically processed. It is wasted. Recovery of the crude at the source, before it becomes seriously water-contaminated, is essential. For example, the PEMEX oil spill in the Gulf of Mexico several years back, lost more than 900,000 barrels of oil. At $20/barrel, the monetary loss amounted to more than $18 million. Applicant believes that if the teachings of this disclosure had been then available, at least 90% of the oil lost at sea could have been recovered.
Another problem in handling pollutant spills is the response time in the dispatch of spill containment devices. Historically, it has required days or even weeks to mobilize those devices and to put them into place. By that time it is often too late. Oftimes, the delay is due to bureaucrats' and environmentalists' wrangling over the best cleanup method. Effective oil-recovery units should be immediately available at all major centers of production and transportation.
Most of the presently-known pollution-control equipment is directed to merely skimming the already-dispersed pollution from the water surface and pumping the scum into holding tanks or pits. Skimmers typically consist of buoyant plastic or rubber curtains suspended from a rope or cable. A typical oil-spill containment boom made by Hurum Marine Inc. of Longueil, Quebec, is their FLEXY 3 oil boom. The curtain has a draft of 24" and a freeboard of 12". The boom is made in 50' sections, any number of which allegedly may be coupled together as required. The boom is handled by small tugs. That sort of oil containment boom is of marginal use in harbors or other relatively protected waters but it is ineffective on the high seas where wave heights of 5 to 15 feet are not uncommon. The waves of the open ocean wash the floating oil slick over the 1-foot freeboard of the boom, rendering the boom completely useless if, indeed, the boom itself actually survives the vicious pounding of the waves. Even in calm water, heavy crude sometimes forms large globs of congealed oil. The shallow-draft curtains tend to slide over the globs rather than raking them in.
Other types of pollution cleanup devices include rope mops, blotters, weir skimmers, oil sorbents and chemical oil dispersants such as supplied for example, by Abasco of Houston, TX. Those techniques may be helpful in cleaning up dispersed pollution in quiet water, but are of little use in containing a spill at the source ab initio.
Another class of oil skimmer and recovery device that allegedly is potentially useful in rough water, is taught by U.S. Pat. No. 4,120,793, issued 10/17/78 to P. J. Strain and U.S. Pat. No. 4,447,348, issued 10/16/84 to W. M. Ayers et al. In those patents, suitable machinery in a sea-going ship or barge presumably sucks up the pollutant-contaminated water through a sluice gate located at the bow or stern of the respective ships, separates the oil from the water and transfers the separated oil to holding tanks or the like for later recovery. In a recent oil spill in Alaska, a foreign-registry ship similar to the above type proved ineffective.
In both patents, the ships are provided with booms much as above described. In rough water, the booms are of no use as I have explained earlier. The effective width of the skimming-swath of the ships is thus restricted to the beam of the ships themselves, a width of perhaps 40 to 60 feet. Such ships would be hard-pressed to cope with the flow of crude from a source such as a ruptured tanker, a broken pipe line or a leaking oil well wherein the oil, flowing upwardly from the leak, has been diffused into a plume having a substantial surface expression. The area of the plume is a function of the depth of the oil leak, the currents and the wind.
A third type of device is exemplified in my U.S. Pat. No. 4,290,714, issued 09/22/81. In that patent, I provided a barge, having a well, the barge being intended to be anchored directly over the source of an oil leak. The barge included a long telescoping sleeve hanging under the well, or alternatively, a plastic tubular sleeve that extended downwards from the well, to be secured to the sea floor around the source of the leak. The objective of the sleeve configuration was to contain the rising plume of pollution to prevent it from becoming dispersed in the water.
There are a number of disadvantages to the '714 device. The barge was immobile once it was anchored in place; its position could not be readily adjusted to maneuver the barge over the surface expression of the leak as the rising oil plume drifted about due to changing ocean currents. The mechanisms for handling the telescoping sleeve were too complicated to be practical. The plastic tubular sleeve, while interesting in concept, would be almost impossible to put in place. The configuration of the barge made it clumsy for tugs to handle in the open sea. Nevertheless, the '714 patent is incorporated herein by reference but only to the extent of its disclosure of pertinent prior art and known techniques for pumping, burning and/or otherwise disposing of recovered oil and/or gas.